The explicit purpose of this research is to contribute to our knowledge and understanding of methamphetamine markets in terms of their organization and operation. The specific aim is to study market dynamics. In support of NIDA's mission to bring "the power of science to bear on drug abuse and addiction," the longer term aim is to improve our ability to study the impact of methamphetamine markets on public health and safety in surrounding communities. The aims of this research will be accomplished through a three-stage process culminating in a comprehensive process study of methamphetamine markets in nine different cities or counties in the United States. Borrowing from recent developments in the study of comprehensive community initiatives, the process study will use a theory of change approach to study local retail markets from the perspectives of local stakeholders including dealers and users (e.g., arrestees, treatment clients), community organizers and providers, local narcotics police, and local public health officials. The initial stage will involve a screening assessment of approximately 18,000 respondents representing U.S. cities and counties to obtain basic information about methamphetamine market activity and participation in local areas. For reasons described in the proposal, these respondents will be narcotics police identified and contacted through local police chiefs. From this screening, 75 cities or counties will be selected for the second stage, which will involve semi-structured telephone interviews with narcotics police identified in the first stage as having the greatest knowledge and ability to understand, appreciate, and access their local methamphetamine markets. They will be asked more detailed questions about local methamphetamine markets, and through an innovative grid approach to locate the markets in precise geographic spots. From analysis of the data collected in the first two stages, 9 cities or counties will be selected for the process study. The goal is to include three cities or counties with established markets, three with emerging markets, and three with new markets. In addition, sites will be selected to represent variability in terms of things like the number and relative stability of local markets. Data will be collected through in depth interviews, focus groups, and systematic observation.